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1.
研究了利用磁控溅射方法制备的柔性硬质纳米复合涂层。结果表明柔性硬质纳米复合涂层具有以下优异性能:是一类具有高硬度、高韧性以及抗裂纹性能的新型涂层;具有较高的硬度模量比(H/E*≥0.1,E*=E/(1-ν~2))、弹性恢复系数(We≥60%)、压应力(σ0)L,且少缺陷的微观结构;生长处于Thornton结构区域相图的T区。磁控溅射非常适合制备纳米复合涂层,文中将对其制备柔性纳米复合薄膜的机理做深入阐述。涂层生长主要受以下3个参数影响:涂层生长过程中吸收的能量Ep,其包含沉积原子携带的能量E_(ca)和轰击离子携带等能量E_(bi)(E_p=E_(ca)+E_(bi)),基体温度Ts和涂层材料的熔点T_m。柔性硬质涂层具有广泛的应用前景,如柔性保护涂层、柔性功能涂层、防脆性涂层开裂的柔性保护涂层以及柔性多层涂层。文中还将详细阐述低温磁控溅射制备柔性纳米复合涂层的原理,并阐述纳米复合涂层及其性能的发展趋势。 相似文献
2.
Thin composite layers (tin in plasma polymer matrix) were prepared in a stainless steel vacuum chamber. An RF powered magnetron with tin target was used to excite the discharge and to activate the monomer species (n-hexane). The gas mixture introduced comprised Ar and n-hexane vapours. The properties of the films and chemical composition were characterized by AFM (surface morphology), TEM and Electron tomography (bulk structure characterization), XPS and FTIR spectroscopy (chemical composition analyses). Current-voltage characteristics were measured to examine the electrical properties of the layers and their dependence on the deposition parameters. 相似文献
3.
Dagmar Chudobova Lukas Nejdl Jaromir Gumulec Olga Krystofova Miguel Angel Merlos Rodrigo Jindrich Kynicky Branislav Ruttkay-Nedecky Pavel Kopel Petr Babula Vojtech Adam Rene Kizek 《International journal of molecular sciences》2013,14(7):13592-13614
Polymers are currently widely used to replace a variety of natural materials with respect to their favourable physical and chemical properties, and due to their economic advantage. One of the most important branches of application of polymers is the production of different products for medical use. In this case, it is necessary to face a significant disadvantage of polymer products due to possible and very common colonization of the surface by various microorganisms that can pose a potential danger to the patient. One of the possible solutions is to prepare polymer with antibacterial/antimicrobial properties that is resistant to bacterial colonization. The aim of this study was to contribute to the development of antimicrobial polymeric material ideal for covering vascular implants with subsequent use in transplant surgery. Therefore, the complexes of polymeric substances (hyaluronic acid and chitosan) with silver nitrate or silver phosphate nanoparticles were created, and their effects on gram-positive bacterial culture of Staphylococcus aureus were monitored. Stages of formation of complexes of silver nitrate and silver phosphate nanoparticles with polymeric compounds were characterized using electrochemical and spectrophotometric methods. Furthermore, the antimicrobial activity of complexes was determined using the methods of determination of growth curves and zones of inhibition. The results of this study revealed that the complex of chitosan, with silver phosphate nanoparticles, was the most suitable in order to have an antibacterial effect on bacterial culture of Staphylococcus aureus. Formation of this complex was under way at low concentrations of chitosan. The results of electrochemical determination corresponded with the results of spectrophotometric methods and verified good interaction and formation of the complex. The complex has an outstanding antibacterial effect and this effect was of several orders higher compared to other investigated complexes. 相似文献
4.
Jindrich Novak Igor Tsukrov Romana Piat Eckart Schnack 《International Journal of Fracture》2002,118(2):31-36
In this paper, we discuss the effect of porosity on the effective elastic properties of unidirectional carbon/carbon composites (carbon fibers in pyrolytic carbon matrix) densified by chemical vapor infiltration (CVI). It is shown that CVI treatment results in formation of irregularly shaped pores randomly oriented in the plane perpendicular to the direction of fiber (transverse plane). These pores are analyzed using numerical conformal mapping procedure, and their contribution to the effective elastic properties is expressed in terms of the cavity compliance contribution tensor. Components of this tensor are found for a variety of typical pores shapes. 相似文献
5.
Josef Pribyl Vaclav Rehout Jindrich Citek Jana Pribylova 《Journal of the science of food and agriculture》2010,90(11):1765-1773
The evaluation of an animal is based on production records, adjusted for environmental effects, which gives a reliable estimation of its breeding value. Highly reliable daughter yield deviations are used as inputs for genetic marker evaluation. Genetic variability is explained by particular loci and background polygenes, both of which are described by the genomic breeding value selection index. Automated genotyping enables the determination of many single‐nucleotide polymorphisms (SNPs) and can increase the reliability of evaluation of young animals (from 0.30 if only the pedigree value is used to 0.60 when the genomic breeding value is applied). However, the introduction of SNPs requires a mixed model with a large number of regressors, in turn requiring new algorithms for the best linear unbiased prediction and BayesB. Here, we discuss a method that uses a genomic relationship matrix to estimate the genomic breeding value of animals directly, without regressors. A one‐step procedure evaluates both genotyped and ungenotyped animals at the same time, and produces one common ranking of all animals in a whole population. An augmented pedigree–genomic relationship matrix and the removal of prerequisites produce more accurate evaluations of all connected animals. Copyright © 2010 Society of Chemical Industry 相似文献
6.
Mach J Samoril T Voborný S Kolíbal M Zlámal J Spousta J Dittrichová L Sikola T 《The Review of scientific instruments》2011,82(8):083302
The paper describes the design and construction of an ion-atomic beam source with an optimized generation of ions for ion-beam-assisted deposition under ultrahigh vacuum (UHV) conditions. The source combines an effusion cell and an electron impact ion source and produces ion beams with ultra-low energies in the range from 30 eV to 200 eV. Decreasing ion beam energy to hyperthermal values (≈10(1) eV) without loosing optimum ionization conditions has been mainly achieved by the incorporation of an ionization chamber with a grid transparent enough for electron and ion beams. In this way the energy and current density of nitrogen ion beams in the order of 10(1) eV and 10(1) nA/cm(2), respectively, have been achieved. The source is capable of growing ultrathin layers or nanostructures at ultra-low energies with a growth rate of several MLs/h. The ion-atomic beam source will be preferentially applied for the synthesis of GaN under UHV conditions. 相似文献
7.
Petr Jandacka Libor M Hlavac Vilem Madr Jindrich Sancer Frantisek Stanek 《International Journal of Fracture》2009,159(1):103-110
Studies of the influence of specimen geometry and size–effect on the K
R
–curves and the related fracture parameters were carried out by the authors (Kumar and Barai 2008b). The present paper is
a supplementary contribution and reports interesting results related to the effect of the loading condition and size–effect
studies on the K
R
–curves associated with the cohesive stress distribution for complete fracture process, the double–K fracture parameters, the CTOD–curves and the process zone length using two different loading conditions (i.e., three–point
bending test and four–point bending test). The laboratory size specimen with initial–notch length/depth ratios 0.3 and 0.5
are considered in the work. The load–crack opening displacement curves for these loading conditions are obtained using well
known version of fictitious crack model. 相似文献
8.
OBJECTIVE: To examine the effects of keyswitch orientation on joint torques. BACKGROUND: The fingertip produces primarily vertical forces during single-finger tapping on a computer keyswitch. However, horizontal force components within the sagittal plane of the finger could reduce net joint torques. METHOD: Eleven participants tapped on a keyswitch oriented in three directions: vertical, tilted 30 degrees such that when pressed it moved away from the user (similar to a positive-tilt keyboard), and tilted 30 degrees such that when pressed it moved toward the user (similar to a negative-tilt keyboard). Participants also tapped on a prototype cantilever keyswitch design in which the key cap moves along the arc of a bending beam gradually away from the user. Miniature electro-optical goniometers measured the finger posture, and a two-axis force sensor measured fingertip forces. RESULTS: Tapping on a keyswitch oriented such that it moves away from the user when pressed reduced net joint torques by 47% relative to tapping on a vertically orientated keyswitch and by 56% relative to tapping on a keyswitch oriented toward the user, whereas the cantilever design resulted in 14% decreases in net joint torque relative to the vertical orientation. CONCLUSION: Reductions of torques resulted from decreasing the moment arm of the fingertip force about the joints. APPLICATION: Keyboard design should incorporate keyswitch mechanism angles along with other postural and geometric constraints to reduce exposure of the finger joints and muscles to force during typing. 相似文献
9.
综述了纳米复合薄膜的硬度增强特性和热稳定性、在高温条件下(≥1 000℃)的抗氧化性和热稳定性、在X射线下呈非晶态的薄膜在高温条件下的热稳定性、以及具有高韧性新型硬质纳米复合薄膜的相关性能。这些新型高韧性硬质纳米复合薄膜具有较低的等效弹性模量E*(H/E*0.1),高弹性恢复系数(We≥60%),优异的摩擦学性能,以及良好的抗断裂能力。等效弹性模量E*=E(1-ν2),E为弹性模量,ν为泊松比。 相似文献
10.